72)
2/9*855=2*855/9=1710/9=190 in prima zi
855-190=665 fire au ramas pt a doua zi
665*3/5=665*3/5=1995/5=399 in a doua zi
190+399=589 s-au plantat in primele 2 zile
855-589= 266 in a treia zi
73)L=150
l=3/5*150=3*150/5=450/5=90
p=2*(l+L)=2*(150+90)=2*240=480
